JP4079514B2 - MMIC low noise amplifier - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an MMIC low noise amplifier that uses FETs and is mainly used in the frequency band of the microwave band, and in particular, by reducing the number of parts of the external matching circuit, it is possible to reduce the component cost and the assembly cost. The present invention relates to an MMIC low noise amplifier.
[0002]
[Prior art]
FIG. 4 is a circuit configuration diagram of a self-bias type MMIC low noise amplifier in which the input matching circuit 14 and the output matching circuit 20 that have been used conventionally are configured by external components. If the inductors 6, 7, 16, and 17 constituting the input matching circuit 14 and the output matching circuit 20 are formed in a GaAs chip, the chip size is greatly increased and the chip cost is increased. The output matching circuit 20 is composed of external parts.
[0003]
The source of the FET 1 is grounded through a self-bias circuit composed of a parallel circuit of a bias resistor 2 and a bypass capacitor 3. The FET 1, the bias resistor 2, and the bypass capacitor 3 are formed in the same chip, and constitute the MMIC chip 19.
[0004]
The gate of the FET 1 is connected to the signal input terminal 4 via the capacitor 5 and the inductor 7, and the inductor 6 is connected between the connection point of the capacitor 5 and the inductor 7 and the ground. The capacitor 5 and the inductors 6 and 7 are made up of external components such as a chip capacitor and a chip inductor, and constitute an input matching circuit 14.
[0005]
On the other hand, the drain of the FET 1 is connected to the signal output terminal 13 via the inductor 16 and the capacitor 18, and the inductor 17 is connected between the connection point of the inductor 16 and the capacitor 18 and the drain voltage (VDD) supply terminal 21. The inductors 16 and 17 and the capacitor 18 are also composed of external parts as described above, and constitute an output matching circuit 20.
[0006]
[Problems to be solved by the invention]
However, the MMIC low noise amplifier has a problem that the number of external parts constituting the input matching circuit and the output matching circuit is as large as six in total, resulting in an increase in parts cost and assembly cost.
[0007]
An object of the present invention is to provide an MMIC low noise amplifier that solves the above-described problems and that can reduce the component cost and assembly cost by reducing the number of external components.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 of the present application is an FET, an input matching circuit connected between the gate terminal and the signal input terminal of the FET, and connected between the drain terminal and the signal output terminal of the FET. In the MMIC low noise amplifier including an output matching circuit and a self-bias circuit connected between the source of the FET and the ground, the output matching circuit includes a feedback resistor having one end connected to the gate terminal and a gate having one end grounded. The other ends of the grounding resistor are connected to each other, the drain terminal is connected to the connection point of the feedback resistor and the gate grounding resistor via the first output matching capacitor, and the connection point is connected to the second output matching. A circuit formed monolithically together with the FET and the self-bias circuit, connected to the signal output terminal via a capacitor for a capacitor, and a drain terminal of the FET Characterized in that comprising a drain voltage supply terminal connected external inductor between.
Further, the invention according to claim 2 of the present application is an FET, an input matching circuit connected between the gate terminal and the signal input terminal of the FET, an output matching circuit connected between the drain terminal and the signal output terminal of the FET, In the MMIC low noise amplifier including a self-bias circuit connected between the source of the FET and the ground, the input matching circuit includes a first spiral inductor having one end grounded, and an other end of the first spiral inductor. One end was connected to the second spiral inductor having the other end connected to the gate terminal, and one end was connected to the connection point of the first and second spiral inductors, and the other end was connected to the signal input terminal. A circuit comprising a capacitor, and the output matching circuit includes a third spiral inductor connected between the drain terminal and the drain voltage supply terminal; The other end of the feedback resistor having one end connected to the gate terminal and the other end of the gate grounding resistor grounded at one end are connected to each other, and the drain terminal is connected to the feedback resistor and the gate grounding resistor via the first output matching capacitor. And connecting the connection point to the signal output terminal via a second output matching capacitor, and the FET, the self-bias circuit, the input matching circuit, and the output matching circuit are monolithic. It is characterized by being formed.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol was attached | subjected to the same or equivalent thing over several drawing.
[0010]
FIG. 1 shows a first embodiment of the present invention. As shown in the figure, the source of the FET 1 is grounded through a self-bias circuit composed of a parallel circuit of a bias resistor 2 and a bypass capacitor 3 as in the conventional device shown in FIG.
[0011]
The gate of the FET 1 is grounded via a feedback resistor 8 and a gate grounding resistor 11. Further, the drain of the FET 1 is connected to the connection point of the feedback resistor 8 and the grounded gate resistor 11 via the first output matching capacitor 10, and the connection point is connected to the signal output via the second output matching capacitor 12. It is connected to the terminal 13.
[0012]
Each of the constituent elements shown above is formed monolithically in the same chip and constitutes the MMIC chip 15. As described above, the feedback resistor 8, the grounded gate resistor 11, the first output matching capacitor 10, and the second output matching capacitor 12 constitute a part of the output matching circuit. Since both occupy a small area, even if they are built in the same chip, the chip area is hardly affected. It is important to select a feedback resistor 8 having a high resistance so as not to deteriorate the noise characteristics of the FET 1.
[0013]
On the other hand, the drain voltage (VDD) of the FET 1 is supplied from the drain voltage supply terminal 21 via the external inductor 9. The inductor 9 also functions as an output matching circuit element. In other words, in the MMIC low noise amplifier according to this configuration, the number of external components necessary for configuring the output matching circuit is only one inductor 9, that is, one choke coil, and the total number of external components is four. On the other hand, it becomes 2/3. Although not described, the input matching circuit 14 is the same as the conventional one shown in FIG.
[0014]
FIG. 2 shows a state of output matching in the first embodiment described above using a Smith chart. As shown in the figure, it can be seen that the drain impedance of the FET 1 is matched to 50Ω by the action of each element constituting the output matching circuit. A point A in FIG. 2 is a drain impedance of FET, moves to the point B by the inductor 9. Further, the impedance moves from the point B to the point C by the first output matching capacitor 10, and moves from the point C to the point D by the feedback resistor 8 and the gate grounding resistor 11. Finally, the second output matching capacitor 12 moves from point D to point E, which becomes the output impedance of the amplifier of FIG. That is, the output impedance of the amplifier is matched to 50Ω which is the characteristic impedance of the line.
[0015]
Note that the eigenvalues of each element constituting the output matching circuit should be selected appropriately according to the set frequency of the amplifier. Is mentioned. That is, when the set frequency of the amplifier is 1.5 GHz, the feedback resistor 8 and the grounded gate resistor 11 are 50 kΩ and 2 kΩ, respectively, and the first output matching capacitor 10 and the second output matching capacitor 12 are 2 pF and 0, respectively. .6 pF and the inductor 9 is 10 nH. This is an example in which good characteristics have been obtained by the inventors' experiments.
[0016]
FIG. 3 shows a second embodiment of the present invention, in which the circuit format is the same as that of the first embodiment, but all the external parts are included in the same chip 25. 1 differs from FIG. 1 in that the inductors 6, 7 and 9 in FIG. 1 are replaced with three spiral inductors 22, 23 and 24 in FIG.
[0017]
Conventionally, a method of replacing an inductor with a spiral inductor has been used as a method of placing an inductor, which is an external component, in a chip. However, the spiral inductor occupies a large area, and the number of use of the spiral inductor greatly affects the chip area, and many expensive GaAs substrates are used. For example, in the conventional low noise amplifier shown in FIG. 4, when all the external components are formed in the chip, it is necessary to replace four inductors 6, 7, 16, and 17 with spiral inductors. As described above, since the cost is not commensurate, the matching circuit disposed at the input / output must be configured with external components.
[0018]
However, in the second embodiment of the present invention, the area of one spiral inductor can be reduced as shown in the figure, so that the chip cost can be reduced and the entire amplifier can be reduced. So good cost performance is realized.
[0019]
【The invention's effect】
As described above, according to the present invention, since the number of parts of the external matching circuit can be reduced, it is possible to provide an MMIC low noise amplifier that enables reduction of parts cost and assembly cost.
[0020]
Even when the input / output matching circuit is built in the same chip, the chip area can be reduced and the chip cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment of the present invention.
FIG. 2 is a diagram showing a state of output matching in the first embodiment of the present invention.
FIG. 3 is a diagram showing a second embodiment of the present invention.
FIG. 4 shows a circuit diagram of a conventional MMIC low noise amplifier.
[Explanation of symbols]
1 FET
2 Bias resistor 3 Bypass capacitor 4 Signal input terminal 5 Capacitors 6, 7, 9 Inductor 8 Feedback resistor 10 First output matching capacitor 11 Gate grounding resistor 12 Second output matching capacitor 13 Signal output terminal 14 External input Matching circuit 15 MMIC chip 20 External output matching circuit 21 Drain voltage supply terminal

Claims (2)

An FET, an input matching circuit connected between the gate terminal and the signal input terminal of the FET, an output matching circuit connected between the drain terminal and the signal output terminal of the FET, and a self connected between the source of the FET and the ground In the MMIC low noise amplifier comprising a bias circuit, the output matching circuit connects the feedback resistor having one end connected to the gate terminal and the other end of the gate grounding resistor grounded at one end, and the drain terminal is connected to the second terminal. The FET connected to the connection point of the feedback resistor and the gate grounding resistor via one output matching capacitor, and the connection point connected to the signal output terminal via a second output matching capacitor; A circuit formed monolithically with the self-bias circuit, and an external connection connected between the drain terminal of the FET and the drain voltage supply terminal MMIC low noise amplifier, characterized by comprising the inductor. An FET, an input matching circuit connected between the gate terminal and the signal input terminal of the FET, an output matching circuit connected between the drain terminal and the signal output terminal of the FET, and a self connected between the source of the FET and the ground In the MMIC low noise amplifier comprising a bias circuit, the input matching circuit includes a first spiral inductor having one end grounded, one end connected to the other end of the first spiral inductor, and the other end connected to the gate. A circuit comprising a second spiral inductor connected to a terminal and a capacitor having one end connected to a connection point of the first and second spiral inductors and the other end connected to the signal input terminal; A third spiral inductor connected between the drain terminal and the drain voltage supply terminal, and one end connected to the gate terminal. Connect the other end of the resistor and the grounded gate resistor with one end grounded, and connect the drain terminal to the connection point of the feedback resistor and the gate grounded resistor via the first output matching capacitor. and circuitry connected to point to the signal output terminal via the second output matching capacitor, the FET, the self-bias circuit, MMIC, characterized in that said input matching circuit and the output matching circuit is formed monolithically Low noise amplifier.

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